Hum problem!!

danman · « **on:** 8 Nov 2009, 02:38 am »

I have just bought an entry level table..........ProJect Debut III had it fitted with an Ortofon 2m Red cartridge and am using a ProJect Phonobox II USB. My problem is that I have an annoying hum that I can't seem to fix no matter what I do. I have tried almost everything from moving the table 20 feet away from my system, changed interconnects, changed outlets, turned the plugs upside down etc.........................The table sounds excellent besides this. I don't even need to have the table running to hear the noise all I need to do is turn up the volume and there you go! I have pinpointed a problem with buzzing from my lighting system and dimmers but the hum is very confusing!!!

Anybody have advice for me???

Wayner · « **Reply #1 on:** 8 Nov 2009, 12:32 pm »

Dimmers are known to be a source problem with audio equipment in general and with phono cartridges in particular. I suspect that you may have an in-expensive dimmer in use that has a poor filter in it. I suggest to either remove the dimmer or go buy a better one (like Leviton) and be aware that this may not fix the problem, you may have to get rid of the dimmer altogether. One way to check if the dimmer is the problem is to have the turntable off, but the system on (set to phono) and have the volume at a moderate level. Turn the dimmer on and change the intensity of the lighting. If the hum's nature changes with the position of the dimmer, that is your problem.

Wayner

danman · « **Reply #2 on:** 8 Nov 2009, 01:13 pm »

Thanks Wayner. I did what you said but that only changes the buzzing sound as you were right, this was the cause of that. The humming however did not change! Seems like something is not grounded properly but I am exausted trying to figure out what! I have the table ground wire hooked up to the ProJect Phonobox ground and that only helps a little but still present. Not sure what else to do!

Niteshade · « **Reply #3 on:** 8 Nov 2009, 01:17 pm »

Could it be a poor connection at the cartridge? I've had this happen recently. One of my ground connections at the cartridge was poor and it would allow a buzz to pass through one channel. I re-seated the wires to the cartridge and the buzz went away. Look at all your contacts. Could you have a relay somewhere?

danman · « **Reply #4 on:** 8 Nov 2009, 01:20 pm »

The table arrived with the changed cartridge and after looking at all connections, things seem fine.

What do you mean by "relay"?

Niteshade · « **Reply #5 on:** 8 Nov 2009, 01:28 pm »

My old Dual has a relay of sorts underneath operated by a cam lobe. It's used to short out the cartridge while the tone arm is being placed on the LP or when it's being removed the the LP at the end of the last track. You proably don't have it- but some turntables have this and it can cause your problem.

Can you measure all resistances to the cartridge with a DMM set to its lowest ohm scale? It still sounds like a contact/wire problem. I assume you connected your turntable's main ground wire to the preamp. Mine fell loose one time and it buzzed like crazy even though the interconnects were securely fastened.

danman · « **Reply #6 on:** 8 Nov 2009, 01:44 pm »

The ground wire is securely fastened but that only decreases the hum a little. I don't have a relay on this table. You must be right about the cartridge as I have tried everything else! I may send it back to the dealer and he has been informed.

Wayner · « **Reply #7 on:** 8 Nov 2009, 07:00 pm »

If I didn't understand, let me ask this question again. Did you say the hum still persisted even with the lights off?

Wayner

roscoeiii · « **Reply #8 on:** 8 Nov 2009, 07:04 pm »

And is this hum coming from the TT chassis or from the speakers? If it is from the chassis, you may need something like the PS Audio Humbuser or Channel Islands XDC-2. The Humbuster fixed my chassis hum which was due to DC on the AC line.

danman · « **Reply #9 on:** 8 Nov 2009, 07:15 pm »

Quote from: Wayner on 8 Nov 2009, 07:00 pm

If I didn't understand, let me ask this question again. Did you say the hum still persisted even with the lights off?

Wayner

Yes. That just decreased the buzzing!

danman · « **Reply #10 on:** 8 Nov 2009, 07:16 pm »

Quote from: roscoeiii on 8 Nov 2009, 07:04 pm

And is this hum coming from the TT chassis or from the speakers? If it is from the chassis, you may need something like the PS Audio Humbuser or Channel Islands XDC-2. The Humbuster fixed my chassis hum which was due to DC on the AC line.

Not sure if I understand what you mean but the humming sound is coming from the speakers as it is amplified.

roscoeiii · « **Reply #11 on:** 8 Nov 2009, 07:21 pm »

OK, if it is coming from the speakers then the Humbuster and XDC-2 would not help you.

Wayner · « **Reply #12 on:** 8 Nov 2009, 08:12 pm »

Go to your circuit breaker panel and find the breaker that the lights (and the dimmer) are on and shut it off. I'll bet the hum goes away.

Wayner

danman · « **Reply #13 on:** 8 Nov 2009, 08:36 pm »

As soon as I get a minute I will do that and let you know. However just before I do, I will say a little prayer..................and if is works, I will send you a "virtual" drink!

Wayner · « **Reply #14 on:** 8 Nov 2009, 08:43 pm »

Well, some dimmers don't completely shut off even when they are "off". Some dimmers are designed really poor. If this works, you will have to find a different dimmer or go back to a regular wall switch. I'm also concerned that your dimmer is on the same branch circuit as your outlets for your stereo system.......

Wayner

danman · « **Reply #15 on:** 8 Nov 2009, 08:46 pm »

Well...................did NOT work! I am going nuts here. I am sure it is not the table! I think I will go to my local dealer and see if he can lend me another phonobox to see if that is the problem!!!!!!!!

Wayner · « **Reply #16 on:** 8 Nov 2009, 08:53 pm »

Here is a different direction. What setting do you have your phono preamp set at? Hopefully not on MC, but on MM as that cartridge is MM. Just have to ask this dumb question to eliminate possibilities.

Wayenr

danman · « **Reply #17 on:** 8 Nov 2009, 08:57 pm »

Yup.............MM.

Wayner · « **Reply #18 on:** 8 Nov 2009, 09:16 pm »

Does your line level preamp have a place to ground? I remember one time a guy had to run a ground from the turntable to the phono preamp and then to the line level preamp. If not you could use just one of the metal screws on the cover. You could do this with just a piece of wire to see if there is any effect or not. Today must be bad ground day as there is another guy on another post with popping sounds in his system. Sometimes tough to figure out "over the phone".

Wayner

guest48077 · « **Reply #19 on:** 8 Nov 2009, 10:10 pm »

I have the exact same table. I have always had a really really low level hum from my table. Not loud enough to hear during music but just loud enough to hear when I put my ear to the speaker. If your hum is a really low level I think it is the table, remember this is just a entry level, 450$ table.

Then again I could be wrong

Hum problem!!

guest48077